Note: Recent molecular studies (Olsen et al., 1994: 740) showed that this family, which is usually called Acetabulariaceae, constitutes a monophyletic group distinct from the Dasycladaceae. The name Polyphysaceae Kützing (1843b: 302, 311, `Polyphyseae') has priority over Acetabulariaceae Nägeli (1847: 158, 252, `Acetabularieae').
Note: The genus Polyphysa Lamarck (1816: 151), with the type species P. australis Lamarck, a taxonomic synonym of P. peniculus (R. Brown ex Turner) C. Agardh (see Note to Acetabularia peniculus), was subsumed as a section of Acetabularia Lamouroux (1812: 185) by Solms-Laubach (1895: 21, 27). In addition to the type, Solms-Laubach placed four other species in the section, namely, A. exigua Solms-Laubach, A. parvula Solms-Laubach, A. moebii Solms-Laubach (treated as a taxonomic synonym of A. parvula in this catalogue), and A. polyphysoides P. Crouan & H. Crouan (in Schramm & Maze, 1865: 42; type locality: Pointe-à-Pitre, Guadeloupe), the latter species not reported from the Indian Ocean. Members of this section were said to differ from those of other sections of Acetabularia by the lack of an inferior corona and the complete separation of the rays of the cap. The genus was again separated from Acetabularia by G. Bailey, Rezak, & Cox (1976), and this treatment has been followed by most recent authors, including Schnetter & Bula Meyer (1982), Womersley (1984), and Berger & Kaever (1992). Most recently, Olsen et al. (1994) concluded that molecular data support the generic separation of A. exigua and A. parvula from other species of Acetabularia, but not the separation of A. peniculus, the type of Polyphysa. The molecular data thus cut across morphological lines. The "Polyphysa clade'' recognized by Olsen et al. represents a genus that may not be called Polyphysa and thus lacks a name. It seems prudent to recognize only one genus until the taxonomic and nomenclatural picture has been clarified.
Madrepora acetabulum Linnaeus, 1758: 793 (syntype localities: Atlantic America; Europe).
Acetabularia acetabulum (Linnaeus) P. Silva, 1952a: 255.—S. Dixit, 1970: 111.
Acetabularia mediterranea Lamouroux, 1816: 249, nom. illeg.—Johnson, 1967b: fig. 2.
INDIAN OCEAN DISTRIBUTION: Sri Lanka.
Note: This species was said by Valet (1969: 608–611) to occur only in the Mediterranean. Acetabularia mediterranea is an illegitimate nomenclatural synonym since Lamouroux cited Tubularia acetabulum (Linnaeus) Linnaeus (1767a: 1303) in the protologue and thus was obligated to maintain the epithet acetabulum.